NOTE: I now have a version for Unity 5.3 and 5.4 which use reflection to integrate with UnityEngine.UI instead of having to build a custom verison. Please see my Unity 5.5 post for this new version.
I have now updated the repo with the 5.4 branch merged in. So simply choose the branch that matches the version you are using. The 5.4 branch has been tested with Unity 5.4.1p2.